It is common practice in commercial and industrial buildings, schools, hospitals, and the like to provide at the public entrances foot mats or grilles for removing dirt from the footwear of persons entering the building. One type of foot grille that is widely used is one that has elongated, narrow individual tread rails of generally T-shaped cross-section joined together with spaces between them through which dirt and water removed by the tread rails can pass to a surface below the grille. The tread rails are joined together by connecting bars that extend transversely through triangular holes in the vertical web portions of the tread rails. Such grilles are assembled by placing the tread rails in a jig, inserting the connecting bars through the holes in a laterally tilted position, and pivoting the connecting bars one by one to an upright position using a special pneumatically powered tool. A foot grille of that type is described and shown in U.S. Pat. No. 4,112,640 (Reifsnyder, 1978).
Another type of known foot grille is composed of elongated, narrow tread rails that are joined by integral tongue and groove hinges or individual coupling strips of "dogbone" cross-section so that the grille, which might better be termed a mat, can be rolled up when it is removed for cleaning the surface below it. Foot mats of this type can be placed directly on a floor or set into a shallow recess in the floor so that the tread surfaces of the rails are flush with the adjacent floor. They are assembled by sliding the rails and the coupling strips, where included, endwise one by one. Examples of foot mats of the hinged, roll-up type are found in U.S. Pats. Nos. 4,029,834 (Bartlett, 1977) and 5,157,804 (Williams, 1992).
Foot grilles and mats of the type disclosed in the above-mentioned patents provide superior performance in use. They are attractive and durable, can be fitted with various tread surfaces, and effectively remove dirt and water from the footwear of persons walking across them. The dirt and water fall or are scraped into the spaces between the tread rails of grilles or through holes in the tread rails of mats onto a surface on which the grille or mat rests. Foot grilles are often installed in a pit that has a drain, and periodically the grille and drain are hosed down to remove accumulated dirt, which drains away. Alternatively, the grille is removed from the pit to enable the pit to be cleaned out. Foot mats can be rolled up to permit the space underneath them to be cleaned thoroughly. Routine cleaning of mats can be done effectively with a commercial vacuum cleaner.
Foot mats and grilles of the type described have some disadvantages. They are relatively difficult to assemble, assembly requires special jigs and tools, and the labor required for assembly is costly. Also, the grille or mat has to be shipped in assembled condition, which usually requires a cumbersome and large shipping configuration.